ltrace: Trace Library Calls

Overview

ltrace intercepts and displays calls to shared library functions used by a program. This is very helpful for understanding program behavior and diagnosing issues.

Main Use Cases

Program debugging
Performance bottleneck analysis
Security vulnerability investigation
Reverse engineering

Key Options

The main options for ltrace control the tracing method, output format, and filtering.

Trace Control

Output and Filtering

Generated command:

Try combining the commands.

Description:

`ltrace` Executes the command.

Combine the above options to virtually execute commands with AI.

Usage Examples

How to trace library calls of a program in various scenarios using ltrace.

Basic Library Call Tracing

ltrace ls

Traces the library calls of the 'ls' command.

View Call Statistics

ltrace -c ls

Shows a summary of call counts and times for library functions of the 'ls' command.

Save Output to File

ltrace -o ls_trace.log ls

Saves the trace results of the 'ls' command to the 'ls_trace.log' file.

Trace Specific Library Functions Only

ltrace -e 'malloc|free' ls

Traces only 'malloc' or 'free' function calls within the 'ls' command.

Trace Child Processes

ltrace -f bash -c "ls"

Traces library calls for both 'bash' and 'ls' when 'ls' is executed within the 'bash' shell.

Installation

ltrace may not be installed by default on most Linux distributions. You can install it using the following commands.

Debian/Ubuntu

sudo apt update && sudo apt install ltrace

Installs ltrace on Debian or Ubuntu-based systems.

CentOS/RHEL/Fedora

sudo dnf install ltrace

Installs ltrace on CentOS, RHEL, or Fedora-based systems.

Tips & Precautions

Points to note and useful tips when using ltrace.

Performance Overhead

ltrace can significantly slow down program execution. Use with caution in production environments.

Difference from strace

ltrace traces library calls, while strace traces system calls. Using both tools together can provide a more complete understanding of program behavior.

Statically Linked Binaries

ltrace is only effective for programs that rely on dynamic libraries. Statically linked binaries have no library calls to trace with ltrace.

Permissions

Root privileges (sudo) may be required to trace other users' processes or system binaries.